B2M and central nervous system cancer: Following stimulation with EGFRvIII-expressing glioma, we demonstrated that both control (i.e., T cells edited for TRAC and B2M, without CAR) and CART-EGFRvIII cells (i.e., T cells edited for TRAC and B2M, with CAR) were positive for surface PD-1 by flow cytometry.